Don't reenumerate files when loading maps.

OpenRA.Game/ModData.cs

@@ -171,10 +171,6 @@ namespace OpenRA
 
 			// Reinitialize all our assets
 			InitializeLoaders(map);
-			ModFiles.LoadFromManifest(Manifest);
-
-			// Mount map package so custom assets can be used.
-			ModFiles.Mount(ModFiles.OpenPackage(map.Path));
 
 			using (new Support.PerfTimer("Map.PreloadRules"))
 				map.PreloadRules();